JPH09144464A - Ring bit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the extent of wear by a method wherein a plurality of cutting guide holes penetrating through from the outer circumferential side to the bore side are provided at a cylindrical shank having a plurality of edge tips provided at the circumference of its front end. SOLUTION: Cuttings moved to the outer circumferential side of a shank 2 are made to flow to the rear side along the outer peripheral face of the shank 2 and during the flow, the cuttings are made to flow into cutting guide holes 8 opening to the outer periphery and are taken into the bore side of the shank 2. Therefore, gathering of cuttings at the outer circumferential side can be reduced and wears on the shank 2 and the outer periphery of pipes on the excavator side can be restrained. As occasion demands, outer edges of the holes 8 are opened to grooves 6 for cuttings. The holes 8 are arranged in radial directions as seen frontally at the bit with their inner ends inclined to the retreating side as seen diagonally, and the cuttings taken smoothly into the holes without opposing to the flow, thereby preventing wears on the outer periphery of the shank and coming-off of edge tips arising from the wear simply at low costs.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a ring bit used as a tool for double pipe type or single pipe type excavation. More specifically, it is a ring bit that has an improved function of discharging powder and has a longer life.

[0002]

2. Description of the Related Art The life of a ring bit depends on whether or not it is possible to discharge the powder. Therefore, as a measure for improving the powder scavenging discharge property, for example, Japanese Utility Model Publication No. 7-32622 proposes to form a powder sizing groove on the inner diameter side of the distal end portion of the cylindrical shank, and in Japanese Utility Model Publication No. 6-49590. Proposals have been made to devise the shape of the milling grooves provided on the tip and the outer periphery of the shank.

[0003]

As shown in FIG. 6, since the powder shaving groove 7 provided on the inner diameter side of the tip portion of the shank 2 increases the amount of the powder taken in to the inner diameter side of the shank, the outer diameter side Although it helps to reduce the amount of powders discharged to the outside, it has no effect on the powders that have flowed into the outer diameter side.

[0004] Further, the milling groove 5 at the tip of the shank and the milling groove 6 at the outer periphery of the shank are provided for the purpose of favorably discharging the milled powder flowing to the outer diameter side, but the desired effect can be obtained. Has not been done. As shown in FIG. 6, normally, the pipe P on the excavator side is
The difference in outer diameter between the ring bit 1 and the ring bit 1 is small, and there is no large gap between the excavation hole and the pipe P so that the dust can escape without resistance.
Accumulation will occur on the outer periphery of the shank 2 and the pipe P. If there is no escape area for the powdered powder, the powdered grooves 5 and 6 at the tip and the outer periphery serve only to expand the accumulating space to some extent.

As described above, the conventional measures relying only on the groove do not provide sufficient dust discharge on the outer diameter side.
As described in Japanese Patent Publication No. 5 and Japanese Utility Model Publication No. 7-17897, the wear on the outer diameter side of the shank is sufficiently suppressed unless another method of fixing cemented carbide or the like to the outer peripheral surface of the shank is adopted. I couldn't.

[0006] A method of suppressing the outer wear by attaching a cemented carbide or the like to the outer circumference of the shank has no effect on the outer wear due to the clogging of the pipe P of the excavator side.

An object of the present invention is to eliminate the above problems.

[0008]

In order to solve the above-mentioned problems, in the present invention, in a ring bit having a plurality of blade tips fixed on the circumference of the end face of a cylindrical shank, the shank is provided. Is provided with a plurality of powder introduction holes penetrating from the outer surface side to the inner diameter surface.

[0009] It is desirable that the powder introduction holes be oriented in a radial direction when the ring bit is viewed from the front and in a direction in which the inner end side is retracted when viewed from the side. Further, it is desirable to open the outer end of this hole to the tip of the shank or the powder-growing groove on the outer periphery of the shank. Even if the shank is opened to the outer periphery of the shank at a position where there is no powdering groove, the effect of installation appears, although it is not as great as when opening to the powdering groove.

The size (diameter) of the hole and the number of the holes to be installed vary depending on the capability of the excavator used.

[0011]

As shown by the arrow in FIG. 5, the powder shavings moved to the outer diameter side of the shank 2 flows rearward along the outer peripheral surface of the shank 2, and in the middle thereof, the powder shavings open to the outer periphery of the shank are introduced. It flows into the hole 8 and is taken into the inner diameter side of the shank 2 through the hole.

In the double pipe excavation, as shown in FIG. 7, the inner bit 9 is set on the shaft core of the ring bit 1. Usually, the difference between the outer diameter of the inner bit 9 and the inner diameter of the ring bit 1 is larger than the difference between the outer diameter of the excavator side pipe P and the excavation hole diameter, and the pressure passed inside the inner rod R is larger. Since water is discharged from the tip of the inner bit and the powder is sucked up by the return flow that passes through the gap between the inner rod and the ring bit, the gap is large and the return flow is small in order to flow the powder with less resistance. It is advantageous to discharge the milling powder into the space on the inner side of the ring bit thus generated. Even in single pipe excavation, it is more advantageous to discharge the powder inside the ring bit with a large gap.

When the bit of the present invention is used, the powder that has flowed to the outer diameter side is taken into the inner diameter side, which is advantageous in terms of discharge, so that the accumulation of powder on the outer diameter side is reduced, and the outer circumference wear of the bit shank, Outer peripheral wear of the excavator side pipe is suppressed.

[0014]

1 to 4 show an embodiment of a ring bit of the present invention.

As shown in the figure, the ring bit 1 has a structure in which a plurality of cutting edge tips 3 are evenly distributed and fixed on the circumference of the end surface of the cylindrical shank 2. The blade tip 3 is made of cemented carbide or the like having excellent wear resistance, and the shank 2 is made of hardened steel or the like having high toughness.

As the blade tip 3, a pointed plate-like tip shown in FIGS. 1 to 3, a bullet-shaped tip shown in FIG. 4, or a tip having a hemispherical tip is often used. The tip 3 is planted by a method in which a seat groove or a hole is provided on the end surface of the tip end of the shank 2 and then brazed and fixed thereto.

Further, in order to reduce the wear of the shank 2 on the outer circumference, as shown in FIG. 3, a tip 4 made of cemented carbide or the like having good wear resistance is arranged behind the tip 3 so as to have an appropriate interval in the circumferential direction. Implantation has been conventionally performed, and the chip 4 can also be used in combination in the present invention if necessary.

The shank 2 is provided with a powder-growing groove 5 at a position avoiding the chip-implanted portion on the end face of the shank 2, and a powder-growing groove 6 continuous with the groove 5 is provided at a predetermined pitch on the outer periphery. It is also conceivable to provide the milling groove 7 of FIG. 6 as necessary.

The above structure is the same as the conventional product. That is, the ring bit 1 of the present invention is characterized in that the shank 2 is provided with the powder refilling introduction hole 8 extending from the outer surface to the inner diameter surface.

In FIG. 1, the outer end of this powder-removing introduction hole 8 is opened to the powder-removing groove 6 on the outer periphery. Further, in FIG. 2, the shank 2 is opened at the position where there is no powdering groove, and in FIG. 3, it is opened to the powdering groove 5 at the tip. Further, in FIG. 4, the holes at the three positions described above are used in combination.

As described above, the outer end of the hole 8 may be set at any position as long as it can take in the powder fed to the shank outer diameter side, but the direction of the hole needs to be careful. The drilling direction shown in the drawings is radial in a front view of the bit and tilted in a direction in which the inner end retracts in a side view is a direction that does not oppose the flow of the powder, and the intake of the powder is smoothly performed.

The diameter of the holes 8 and the number of the holes 8 to be installed are determined in consideration of this point, because the amount of dust generation changes depending on the capability of the excavator.

[0023]

As described above, in the ring bit of the present invention, the shank is provided with a powder introduction hole, and the powder discharged to the outer diameter side from the hole is forcibly taken in to the inner diameter side. Therefore, it is possible to reduce the outer edge wear of the shank and the drop of the cutting edge tip due to the wear by a relatively simple and inexpensive method of making two or more holes in the shank, and suppress the cost increase. It is possible to improve the service life of all.

Further, due to the reduction of the accumulated powder on the outer diameter side, the outer peripheral wear of the pipe on the excavator side is suppressed, which leads to the high efficiency and the low cost of the soil drilling.

[Brief description of the drawings]

FIG. 1A is a partially cutaway side view showing an embodiment of a ring bit according to the present invention. FIG. 1B is a front view of the same bit.

FIG. 2A is a partially cutaway side view of another embodiment. FIG. 2B is a front view of the same.

FIG. 3A is a partially cutaway side view of still another embodiment. FIG. 3B is a front view of the same.

FIG. 4A is a partially cutaway side view of still another embodiment. FIG. 4B is a front view of the same.

FIG. 5 is an explanatory view of the operation of the ring bit of this invention.

FIG. 6 is an explanatory view of the operation of a conventional ring bit.

FIG. 7 (a): a diagram showing an example of a powder discharge mechanism in a double pipe type drill bit (b): a front view of the above drill bit

[Explanation of symbols]

 1 Ring Bit 2 Shank 3 Cutting Edge Tip 4 Tip for Protecting External Surface 5 Milling Groove on Tip 6 Milling Groove on Outer Edge 7 Milling Groove on Inner Diameter Side 8 Milling Introduction Hole 9 Inner Bit P Excavator Side Pipe

Claims (1)

[Claims] 1. A ring bit having a plurality of blade tips fixed to the circumference of the end face of a cylindrical shank, wherein the shank is provided with a plurality of powder introduction holes penetrating from the outer surface side to the inner diameter surface. A ring bit that is characterized.